Brake problem

I wasn't sure on what section to post this in, and if its in the wrong section, mods please move.

I have a 1986 crew cab dually, just recently my brakes have almost stopped working completely. About two days ago I noticed that I didn't have any brake pressure. I checked for leaks, found nothing. I checked the master cylinder, and it was low, so I topped it off, and they still dont work. seems like its the front thats bad. If I pump the pedal, it slowly builds pressure and the pedal wont go to the floor. When I hit the brakes, the pedal goes to the floor, and the truck doesn't stop, but the rear wheels can lock up and skid.
I'm not too familiar with this type of braking system since there is no power booster. Does this system have a proportioning valve?

Any ideas on what could be wrong?

Thanks!

1. There is no "wrong section". DS is pretty much an organizational abortion.

2. It's likely the Hydro-boost gone bad. Not an uncommon occurrence. Under $200 w/ core at most parts houses.

Right on. Thanks for the reply!

I'm gonna call and get some prices tomorrow.

Yes they do have a proportioning valve. I would think if it was the hydro boost you wouldn't have power brakes but they would work pretty much normally. But I'll be honest I don't really know. The hydro boost is just a hydraulic booster as opposed to a vacuum operated booster.

When the hydroboost completely fails, you'll end up with an extremely hard pedal. For an example, shut off your engine then try to stop. I don't know what the story is on the little reserve cannister on the unit but it hasn't done me any favors lately...

Richard

Yeah, I don't have a clue...I was really just talking out of my ass.

If you can't find any leaks maybe it was just low from wear on the pads/shoes. Was it low enough that you got air in the system? Has it lost any fluid since you filled it?

Just wanted to update everyone on the problem in case anyone else runs into the same issue.

So I got a new master cylinder, put it in, flushed out all the old brake fluid, and put in new fluid. Bled the brakes from the pass. side rear first, then driver rear, the pass. front, then driver front, and now everything works fine.

New master cylinder from my local autopart store with lifetime warranty was under $50 with a core exchange.